An electronic device may include circuitry that is controlled by or that utilizes signals that have a defined phase relationship with one another. For example, an electronic device may include different circuits that operate at different speeds. In such a case, a set of clock signals (e.g., a clock tree) may be provided at the device to control the operation of these different circuits. In addition, specific phase relationships may be defined for these clock signals so that the circuits interact with one another in a designated manner.
Under certain circumstances, an electronic device may be unable to maintain the desired phase relationships for a set of signals over time. For example, the phase relationships between different signals of a clock tree that exist after the electronic device is powered on may be different than the phase relationships that existed before the electronic device was powered off.
To maintain such phase relationships over time, the timing circuitry of an electronic device may be left powered on and the electronic device may employ a relatively complicated timing control mechanism such as a phase lock loop. Timing control schemes such as these, however, may consume a relatively large amount of power even when the electronic device is not processing data.
In accordance with common practice the various features illustrated in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the drawings may be simplified for clarity. Thus, the drawings may not depict all of the components of a given apparatus or method. Finally, like reference numerals may be used to denote like features throughout the specification and figures.